poolalloc/lib/DSA/BottomUpClosure.cpp - llvm-archive - Git at Google

 //===- BottomUpClosure.cpp - Compute bottom-up interprocedural closure ----===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file was developed by the LLVM research group and is distributed under
 // the University of Illinois Open Source License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file implements the BUDataStructures class, which represents the
 // Bottom-Up Interprocedural closure of the data structure graph over the
 // program.  This is useful for applications like pool allocation, but **not**
 // applications like alias analysis.
 //
 //===----------------------------------------------------------------------===//

 #define DEBUG_TYPE "bu_dsa"
 #include "dsa/DataStructure.h"
 #include "dsa/DSGraph.h"
 #include "llvm/Module.h"
 #include "llvm/DerivedTypes.h"
 #include "llvm/ADT/Statistic.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/Timer.h"
 using namespace llvm;

 namespace {
   STATISTIC (MaxSCC, "Maximum SCC Size in Call Graph");
   STATISTIC (NumBUInlines, "Number of graphs inlined");
   STATISTIC (NumCallEdges, "Number of 'actual' call edges");

   RegisterPass<BUDataStructures>
   X("dsa-bu", "Bottom-up Data Structure Analysis");
 }

 char BUDataStructures::ID;

 // run - Calculate the bottom up data structure graphs for each function in the
 // program.
 //
 bool BUDataStructures::runOnModule(Module &M) {
   StdLibDataStructures &LocalDSA = getAnalysis<StdLibDataStructures>();
   setGraphSource(&LocalDSA);
   setTargetData(LocalDSA.getTargetData());
   setGraphClone(false);
   GlobalECs = LocalDSA.getGlobalECs();

   GlobalsGraph = new DSGraph(LocalDSA.getGlobalsGraph(), GlobalECs);
   GlobalsGraph->setPrintAuxCalls();

   IndCallGraphMap = new std::map<std::vector<Function*>,
                            std::pair<DSGraph*, std::vector<DSNodeHandle> > >();

   std::vector<Function*> Stack;
   hash_map<Function*, unsigned> ValMap;
   unsigned NextID = 1;

   Function *MainFunc = M.getFunction("main");
   if (MainFunc)
     calculateGraphs(MainFunc, Stack, NextID, ValMap);

   // Calculate the graphs for any functions that are unreachable from main...
   for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
     if (!I->isDeclaration() && !DSInfo.count(I)) {
       if (MainFunc)
         DOUT << "*** BU: Function unreachable from main: "
              << I->getName() << "\n";
       calculateGraphs(I, Stack, NextID, ValMap);     // Calculate all graphs.
     }

   // If we computed any temporary indcallgraphs, free them now.
   for (std::map<std::vector<Function*>,
          std::pair<DSGraph*, std::vector<DSNodeHandle> > >::iterator I =
          IndCallGraphMap->begin(), E = IndCallGraphMap->end(); I != E; ++I) {
     I->second.second.clear();  // Drop arg refs into the graph.
     delete I->second.first;
   }
   delete IndCallGraphMap;

   // At the end of the bottom-up pass, the globals graph becomes complete.
   // FIXME: This is not the right way to do this, but it is sorta better than
   // nothing!  In particular, externally visible globals and unresolvable call
   // nodes at the end of the BU phase should make things that they point to
   // incomplete in the globals graph.
   //
   GlobalsGraph->removeTriviallyDeadNodes();
   GlobalsGraph->maskIncompleteMarkers();

   // Mark external globals incomplete.
   GlobalsGraph->markIncompleteNodes(DSGraph::IgnoreGlobals);

   formGlobalECs();

   // Merge the globals variables (not the calls) from the globals graph back
   // into the main function's graph so that the main function contains all of
   // the information about global pools and GV usage in the program.
   if (MainFunc && !MainFunc->isDeclaration()) {
     DSGraph &MainGraph = getOrCreateGraph(MainFunc);
     const DSGraph &GG = *MainGraph.getGlobalsGraph();
     ReachabilityCloner RC(MainGraph, GG,
                           DSGraph::DontCloneCallNodes |
                           DSGraph::DontCloneAuxCallNodes);

     // Clone the global nodes into this graph.
     for (DSScalarMap::global_iterator I = GG.getScalarMap().global_begin(),
            E = GG.getScalarMap().global_end(); I != E; ++I)
       if (isa<GlobalVariable>(*I))
         RC.getClonedNH(GG.getNodeForValue(*I));

     MainGraph.maskIncompleteMarkers();
     MainGraph.markIncompleteNodes(DSGraph::MarkFormalArgs |
                                   DSGraph::IgnoreGlobals);
   }

   NumCallEdges += ActualCallees.size();

   return false;
 }

 static void GetAllCallees(const DSCallSite &CS,
                           std::vector<Function*> &Callees) {
   if (CS.isDirectCall()) {
     Callees.push_back(CS.getCalleeFunc());
   } else if (!CS.getCalleeNode()->isIncompleteNode()) {
     // Get all callees.
     CS.getCalleeNode()->addFullFunctionList(Callees);
   }
 }

 /// GetAllAuxCallees - Return a list containing all of the resolvable callees in
 /// the aux list for the specified graph in the Callees vector.
 static void GetAllAuxCallees(DSGraph &G, std::vector<Function*> &Callees) {
   Callees.clear();
   for (DSGraph::afc_iterator I = G.afc_begin(), E = G.afc_end(); I != E; ++I)
     GetAllCallees(*I, Callees);
 }

 unsigned BUDataStructures::calculateGraphs(Function *F,
                                            std::vector<Function*> &Stack,
                                            unsigned &NextID,
                                            hash_map<Function*, unsigned> &ValMap) {
   assert(!ValMap.count(F) && "Shouldn't revisit functions!");
   unsigned Min = NextID++, MyID = Min;
   ValMap[F] = Min;
   Stack.push_back(F);

   DSGraph &Graph = getOrCreateGraph(F);

   // Find all callee functions.
   std::vector<Function*> CalleeFunctions;
   GetAllAuxCallees(Graph, CalleeFunctions);

   // The edges out of the current node are the call site targets...
   for (unsigned i = 0, e = CalleeFunctions.size(); i != e; ++i) {
     Function *Callee = CalleeFunctions[i];
     unsigned M;
     // Have we visited the destination function yet?
     hash_map<Function*, unsigned>::iterator It = ValMap.find(Callee);
     if (It == ValMap.end())  // No, visit it now.
       M = calculateGraphs(Callee, Stack, NextID, ValMap);
     else                    // Yes, get it's number.
       M = It->second;
     if (M < Min) Min = M;
   }

   assert(ValMap[F] == MyID && "SCC construction assumption wrong!");
   if (Min != MyID)
     return Min;         // This is part of a larger SCC!

   // If this is a new SCC, process it now.
   if (Stack.back() == F) {           // Special case the single "SCC" case here.
     DOUT << "Visiting single node SCC #: " << MyID << " fn: "
          << F->getName() << "\n";
     Stack.pop_back();
     DOUT << "  [BU] Calculating graph for: " << F->getName()<< "\n";
     calculateGraph(Graph);
     DOUT << "  [BU] Done inlining: " << F->getName() << " ["
          << Graph.getGraphSize() << "+" << Graph.getAuxFunctionCalls().size()
          << "]\n";

     if (MaxSCC < 1) MaxSCC = 1;

     // Should we revisit the graph?  Only do it if there are now new resolvable
     // callees.
     GetAllAuxCallees(Graph, CalleeFunctions);
     if (!CalleeFunctions.empty()) {
       DOUT << "Recalculating " << F->getName() << " due to new knowledge\n";
       ValMap.erase(F);
       return calculateGraphs(F, Stack, NextID, ValMap);
     } else {
       ValMap[F] = ~0U;
     }
     return MyID;

   } else {
     // SCCFunctions - Keep track of the functions in the current SCC
     //
     std::vector<DSGraph*> SCCGraphs;

     unsigned SCCSize = 1;
     Function *NF = Stack.back();
     ValMap[NF] = ~0U;
     DSGraph &SCCGraph = getDSGraph(*NF);

     // First thing first, collapse all of the DSGraphs into a single graph for
     // the entire SCC.  Splice all of the graphs into one and discard all of the
     // old graphs.
     //
     while (NF != F) {
       Stack.pop_back();
       NF = Stack.back();
       ValMap[NF] = ~0U;

       DSGraph &NFG = getDSGraph(*NF);

       // Update the Function -> DSG map.
       for (DSGraph::retnodes_iterator I = NFG.retnodes_begin(),
              E = NFG.retnodes_end(); I != E; ++I)
         DSInfo[I->first] = &SCCGraph;

       SCCGraph.spliceFrom(NFG);
       delete &NFG;

       ++SCCSize;
     }
     Stack.pop_back();

     DOUT << "Calculating graph for SCC #: " << MyID << " of size: "
          << SCCSize << "\n";

     // Compute the Max SCC Size.
     if (MaxSCC < SCCSize)
       MaxSCC = SCCSize;

     // Clean up the graph before we start inlining a bunch again...
     SCCGraph.removeDeadNodes(DSGraph::KeepUnreachableGlobals);

     // Now that we have one big happy family, resolve all of the call sites in
     // the graph...
     calculateGraph(SCCGraph);
     DOUT << "  [BU] Done inlining SCC  [" << SCCGraph.getGraphSize()
          << "+" << SCCGraph.getAuxFunctionCalls().size() << "]\n"
          << "DONE with SCC #: " << MyID << "\n";

     // We never have to revisit "SCC" processed functions...
     return MyID;
   }

   return MyID;  // == Min
 }


 // releaseMemory - If the pass pipeline is done with this pass, we can release
 // our memory... here...
 //
 void BUDataStructures::releaseMyMemory() {
   for (hash_map<Function*, DSGraph*>::iterator I = DSInfo.begin(),
          E = DSInfo.end(); I != E; ++I) {
     I->second->getReturnNodes().erase(I->first);
     if (I->second->getReturnNodes().empty())
       delete I->second;
   }

   // Empty map so next time memory is released, data structures are not
   // re-deleted.
   DSInfo.clear();
   delete GlobalsGraph;
   GlobalsGraph = 0;
 }

 DSGraph &BUDataStructures::CreateGraphForExternalFunction(const Function &Fn) {
   Function *F = const_cast<Function*>(&Fn);
   DSGraph *DSG = new DSGraph(GlobalECs, GlobalsGraph->getTargetData());
   DSInfo[F] = DSG;
   DSG->setGlobalsGraph(GlobalsGraph);
   DSG->setPrintAuxCalls();

   // Add function to the graph.
   DSG->getReturnNodes().insert(std::make_pair(F, DSNodeHandle()));

   if (F->getName() == "free") { // Taking the address of free.

     // Free should take a single pointer argument, mark it as heap memory.
     DSNodeHandle N(new DSNode(0, DSG));
     N.getNode()->setHeapMarker();
     DSG->getNodeForValue(F->arg_begin()).mergeWith(N);

   } else {
     cerr << "Unrecognized external function: " << F->getName() << "\n";
     abort();
   }

   return *DSG;
 }

 void BUDataStructures::calculateGraph(DSGraph &Graph) {
   // If this graph contains the main function, clone the globals graph into this
   // graph before we inline callees and other fun stuff.
   bool ContainsMain = false;
   DSGraph::ReturnNodesTy &ReturnNodes = Graph.getReturnNodes();

   for (DSGraph::ReturnNodesTy::iterator I = ReturnNodes.begin(),
          E = ReturnNodes.end(); I != E; ++I)
     if (I->first->hasExternalLinkage() && I->first->getName() == "main") {
       ContainsMain = true;
       break;
     }

   // If this graph contains main, copy the contents of the globals graph over.
   // Note that this is *required* for correctness.  If a callee contains a use
   // of a global, we have to make sure to link up nodes due to global-argument
   // bindings.
   if (ContainsMain) {
     const DSGraph &GG = *Graph.getGlobalsGraph();
     ReachabilityCloner RC(Graph, GG,
                           DSGraph::DontCloneCallNodes |
                           DSGraph::DontCloneAuxCallNodes);

     // Clone the global nodes into this graph.
     for (DSScalarMap::global_iterator I = GG.getScalarMap().global_begin(),
            E = GG.getScalarMap().global_end(); I != E; ++I)
       if (isa<GlobalVariable>(*I))
         RC.getClonedNH(GG.getNodeForValue(*I));
   }


   // Move our call site list into TempFCs so that inline call sites go into the
   // new call site list and doesn't invalidate our iterators!
   std::list<DSCallSite> TempFCs;
   std::list<DSCallSite> &AuxCallsList = Graph.getAuxFunctionCalls();
   TempFCs.swap(AuxCallsList);

   bool Printed = false;
   std::vector<Function*> CalledFuncs;
   while (!TempFCs.empty()) {
     DSCallSite &CS = *TempFCs.begin();

     CalledFuncs.clear();

     // Fast path for noop calls.  Note that we don't care about merging globals
     // in the callee with nodes in the caller here.
     if (CS.getRetVal().isNull() && CS.getNumPtrArgs() == 0) {
       TempFCs.erase(TempFCs.begin());
       continue;
     }

     GetAllCallees(CS, CalledFuncs);

     if (CalledFuncs.empty()) {
       // Remember that we could not resolve this yet!
       AuxCallsList.splice(AuxCallsList.end(), TempFCs, TempFCs.begin());
       continue;
     } else {
       DSGraph *GI;
       Instruction *TheCall = CS.getCallSite().getInstruction();

       if (CalledFuncs.size() == 1) {
         Function *Callee = CalledFuncs[0];
         ActualCallees.insert(std::make_pair(TheCall, Callee));

         // Get the data structure graph for the called function.
         GI = &getDSGraph(*Callee);  // Graph to inline
         DOUT << "    Inlining graph for " << Callee->getName()
              << "[" << GI->getGraphSize() << "+"
              << GI->getAuxFunctionCalls().size() << "] into '"
              << Graph.getFunctionNames() << "' [" << Graph.getGraphSize() <<"+"
              << Graph.getAuxFunctionCalls().size() << "]\n";
         Graph.mergeInGraph(CS, *Callee, *GI,
                            DSGraph::StripAllocaBit|DSGraph::DontCloneCallNodes);
         ++NumBUInlines;
       } else {
         if (!Printed)
           DEBUG(std::cerr << "In Fns: " << Graph.getFunctionNames() << "\n");
           DEBUG(std::cerr << "  calls " << CalledFuncs.size()
                   << " fns from site: " << CS.getCallSite().getInstruction()
                   << "  " << *CS.getCallSite().getInstruction());
         DEBUG(std::cerr << "   Fns =");
         unsigned NumPrinted = 0;

         for (std::vector<Function*>::iterator I = CalledFuncs.begin(),
                E = CalledFuncs.end(); I != E; ++I) {
           if (NumPrinted++ < 8) cerr << " " << (*I)->getName();

           // Add the call edges to the call graph.
           ActualCallees.insert(std::make_pair(TheCall, *I));
         }
         cerr << "\n";

         // See if we already computed a graph for this set of callees.
         std::sort(CalledFuncs.begin(), CalledFuncs.end());
         std::pair<DSGraph*, std::vector<DSNodeHandle> > &IndCallGraph =
           (*IndCallGraphMap)[CalledFuncs];

         if (IndCallGraph.first == 0) {
           std::vector<Function*>::iterator I = CalledFuncs.begin(),
             E = CalledFuncs.end();

           // Start with a copy of the first graph.
           GI = IndCallGraph.first = new DSGraph(getDSGraph(**I), GlobalECs);
           GI->setGlobalsGraph(Graph.getGlobalsGraph());
           std::vector<DSNodeHandle> &Args = IndCallGraph.second;

           // Get the argument nodes for the first callee.  The return value is
           // the 0th index in the vector.
           GI->getFunctionArgumentsForCall(*I, Args);

           // Merge all of the other callees into this graph.
           for (++I; I != E; ++I) {
             // If the graph already contains the nodes for the function, don't
             // bother merging it in again.
             if (!GI->containsFunction(*I)) {
               GI->cloneInto(getDSGraph(**I));
               ++NumBUInlines;
             }

             std::vector<DSNodeHandle> NextArgs;
             GI->getFunctionArgumentsForCall(*I, NextArgs);
             unsigned i = 0, e = Args.size();
             for (; i != e; ++i) {
               if (i == NextArgs.size()) break;
               Args[i].mergeWith(NextArgs[i]);
             }
             for (e = NextArgs.size(); i != e; ++i)
               Args.push_back(NextArgs[i]);
           }

           // Clean up the final graph!
           GI->removeDeadNodes(DSGraph::KeepUnreachableGlobals);
         } else {
           cerr << "***\n*** RECYCLED GRAPH ***\n***\n";
         }

         GI = IndCallGraph.first;

         // Merge the unified graph into this graph now.
         DOUT << "    Inlining multi callee graph "
              << "[" << GI->getGraphSize() << "+"
              << GI->getAuxFunctionCalls().size() << "] into '"
              << Graph.getFunctionNames() << "' [" << Graph.getGraphSize() <<"+"
              << Graph.getAuxFunctionCalls().size() << "]\n";

         Graph.mergeInGraph(CS, IndCallGraph.second, *GI,
                            DSGraph::StripAllocaBit |
                            DSGraph::DontCloneCallNodes);
         ++NumBUInlines;
       }
     }
     TempFCs.erase(TempFCs.begin());
   }

   // Recompute the Incomplete markers
   Graph.maskIncompleteMarkers();
   Graph.markIncompleteNodes(DSGraph::MarkFormalArgs);

   // Delete dead nodes.  Treat globals that are unreachable but that can
   // reach live nodes as live.
   Graph.removeDeadNodes(DSGraph::KeepUnreachableGlobals);

   // When this graph is finalized, clone the globals in the graph into the
   // globals graph to make sure it has everything, from all graphs.
   DSScalarMap &MainSM = Graph.getScalarMap();
   ReachabilityCloner RC(*GlobalsGraph, Graph, DSGraph::StripAllocaBit);

   // Clone everything reachable from globals in the function graph into the
   // globals graph.
   for (DSScalarMap::global_iterator I = MainSM.global_begin(),
          E = MainSM.global_end(); I != E; ++I)
     RC.getClonedNH(MainSM[*I]);

   //Graph.writeGraphToFile(cerr, "bu_" + F.getName());
 }

 static const Function *getFnForValue(const Value *V) {
   if (const Instruction *I = dyn_cast<Instruction>(V))
     return I->getParent()->getParent();
   else if (const Argument *A = dyn_cast<Argument>(V))
     return A->getParent();
   else if (const BasicBlock *BB = dyn_cast<BasicBlock>(V))
     return BB->getParent();
   return 0;
 }

 /// deleteValue/copyValue - Interfaces to update the DSGraphs in the program.
 /// These correspond to the interfaces defined in the AliasAnalysis class.
 void BUDataStructures::deleteValue(Value *V) {
   if (const Function *F = getFnForValue(V)) {  // Function local value?
     // If this is a function local value, just delete it from the scalar map!
     getDSGraph(*F).getScalarMap().eraseIfExists(V);
     return;
   }

   if (Function *F = dyn_cast<Function>(V)) {
     assert(getDSGraph(*F).getReturnNodes().size() == 1 &&
            "cannot handle scc's");
     delete DSInfo[F];
     DSInfo.erase(F);
     return;
   }

   assert(!isa<GlobalVariable>(V) && "Do not know how to delete GV's yet!");
 }

 void BUDataStructures::copyValue(Value *From, Value *To) {
   if (From == To) return;
   if (const Function *F = getFnForValue(From)) {  // Function local value?
     // If this is a function local value, just delete it from the scalar map!
     getDSGraph(*F).getScalarMap().copyScalarIfExists(From, To);
     return;
   }

   if (Function *FromF = dyn_cast<Function>(From)) {
     Function *ToF = cast<Function>(To);
     assert(!DSInfo.count(ToF) && "New Function already exists!");
     DSGraph *NG = new DSGraph(getDSGraph(*FromF), GlobalECs);
     DSInfo[ToF] = NG;
     assert(NG->getReturnNodes().size() == 1 && "Cannot copy SCC's yet!");

     // Change the Function* is the returnnodes map to the ToF.
     DSNodeHandle Ret = NG->retnodes_begin()->second;
     NG->getReturnNodes().clear();
     NG->getReturnNodes()[ToF] = Ret;
     return;
   }

   if (const Function *F = getFnForValue(To)) {
     DSGraph &G = getDSGraph(*F);
     G.getScalarMap().copyScalarIfExists(From, To);
     return;
   }

   cerr << *From;
   cerr << *To;
   assert(0 && "Do not know how to copy this yet!");
   abort();
 }
	//===- BottomUpClosure.cpp - Compute bottom-up interprocedural closure ----===//
	//
	// The LLVM Compiler Infrastructure
	//
	// This file was developed by the LLVM research group and is distributed under
	// the University of Illinois Open Source License. See LICENSE.TXT for details.
	//
	//===----------------------------------------------------------------------===//
	//
	// This file implements the BUDataStructures class, which represents the
	// Bottom-Up Interprocedural closure of the data structure graph over the
	// program. This is useful for applications like pool allocation, but not
	// applications like alias analysis.
	//
	//===----------------------------------------------------------------------===//

	#define DEBUG_TYPE "bu_dsa"
	#include "dsa/DataStructure.h"
	#include "dsa/DSGraph.h"
	#include "llvm/Module.h"
	#include "llvm/DerivedTypes.h"
	#include "llvm/ADT/Statistic.h"
	#include "llvm/Support/CommandLine.h"
	#include "llvm/Support/Debug.h"
	#include "llvm/Support/Timer.h"
	using namespace llvm;

	namespace {
	STATISTIC (MaxSCC, "Maximum SCC Size in Call Graph");
	STATISTIC (NumBUInlines, "Number of graphs inlined");
	STATISTIC (NumCallEdges, "Number of 'actual' call edges");

	RegisterPass<BUDataStructures>
	X("dsa-bu", "Bottom-up Data Structure Analysis");
	}

	char BUDataStructures::ID;

	// run - Calculate the bottom up data structure graphs for each function in the
	// program.
	//
	bool BUDataStructures::runOnModule(Module &M) {
	StdLibDataStructures &LocalDSA = getAnalysis<StdLibDataStructures>();
	setGraphSource(&LocalDSA);
	setTargetData(LocalDSA.getTargetData());
	setGraphClone(false);
	GlobalECs = LocalDSA.getGlobalECs();

	GlobalsGraph = new DSGraph(LocalDSA.getGlobalsGraph(), GlobalECs);
	GlobalsGraph->setPrintAuxCalls();

	IndCallGraphMap = new std::map<std::vector<Function*>,
	std::pair<DSGraph*, std::vector<DSNodeHandle> > >();

	std::vector<Function*> Stack;
	hash_map<Function*, unsigned> ValMap;
	unsigned NextID = 1;

	Function *MainFunc = M.getFunction("main");
	if (MainFunc)
	calculateGraphs(MainFunc, Stack, NextID, ValMap);

	// Calculate the graphs for any functions that are unreachable from main...
	for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
	if (!I->isDeclaration() && !DSInfo.count(I)) {
	if (MainFunc)
	DOUT << "*** BU: Function unreachable from main: "
	<< I->getName() << "\n";
	calculateGraphs(I, Stack, NextID, ValMap); // Calculate all graphs.
	}

	// If we computed any temporary indcallgraphs, free them now.
	for (std::map<std::vector<Function*>,
	std::pair<DSGraph*, std::vector<DSNodeHandle> > >::iterator I =
	IndCallGraphMap->begin(), E = IndCallGraphMap->end(); I != E; ++I) {
	I->second.second.clear(); // Drop arg refs into the graph.
	delete I->second.first;
	}
	delete IndCallGraphMap;

	// At the end of the bottom-up pass, the globals graph becomes complete.
	// FIXME: This is not the right way to do this, but it is sorta better than
	// nothing! In particular, externally visible globals and unresolvable call
	// nodes at the end of the BU phase should make things that they point to
	// incomplete in the globals graph.
	//
	GlobalsGraph->removeTriviallyDeadNodes();
	GlobalsGraph->maskIncompleteMarkers();

	// Mark external globals incomplete.
	GlobalsGraph->markIncompleteNodes(DSGraph::IgnoreGlobals);

	formGlobalECs();

	// Merge the globals variables (not the calls) from the globals graph back
	// into the main function's graph so that the main function contains all of
	// the information about global pools and GV usage in the program.
	if (MainFunc && !MainFunc->isDeclaration()) {
	DSGraph &MainGraph = getOrCreateGraph(MainFunc);
	const DSGraph &GG = *MainGraph.getGlobalsGraph();
	ReachabilityCloner RC(MainGraph, GG,
	DSGraph::DontCloneCallNodes \|
	DSGraph::DontCloneAuxCallNodes);

	// Clone the global nodes into this graph.
	for (DSScalarMap::global_iterator I = GG.getScalarMap().global_begin(),
	E = GG.getScalarMap().global_end(); I != E; ++I)
	if (isa<GlobalVariable>(*I))
	RC.getClonedNH(GG.getNodeForValue(*I));

	MainGraph.maskIncompleteMarkers();
	MainGraph.markIncompleteNodes(DSGraph::MarkFormalArgs \|
	DSGraph::IgnoreGlobals);
	}

	NumCallEdges += ActualCallees.size();

	return false;
	}

	static void GetAllCallees(const DSCallSite &CS,
	std::vector<Function*> &Callees) {
	if (CS.isDirectCall()) {
	Callees.push_back(CS.getCalleeFunc());
	} else if (!CS.getCalleeNode()->isIncompleteNode()) {
	// Get all callees.
	CS.getCalleeNode()->addFullFunctionList(Callees);
	}
	}

	/// GetAllAuxCallees - Return a list containing all of the resolvable callees in
	/// the aux list for the specified graph in the Callees vector.
	static void GetAllAuxCallees(DSGraph &G, std::vector<Function*> &Callees) {
	Callees.clear();
	for (DSGraph::afc_iterator I = G.afc_begin(), E = G.afc_end(); I != E; ++I)
	GetAllCallees(*I, Callees);
	}

	unsigned BUDataStructures::calculateGraphs(Function *F,
	std::vector<Function*> &Stack,
	unsigned &NextID,
	hash_map<Function*, unsigned> &ValMap) {
	assert(!ValMap.count(F) && "Shouldn't revisit functions!");
	unsigned Min = NextID++, MyID = Min;
	ValMap[F] = Min;
	Stack.push_back(F);

	DSGraph &Graph = getOrCreateGraph(F);

	// Find all callee functions.
	std::vector<Function*> CalleeFunctions;
	GetAllAuxCallees(Graph, CalleeFunctions);

	// The edges out of the current node are the call site targets...
	for (unsigned i = 0, e = CalleeFunctions.size(); i != e; ++i) {
	Function *Callee = CalleeFunctions[i];
	unsigned M;
	// Have we visited the destination function yet?
	hash_map<Function*, unsigned>::iterator It = ValMap.find(Callee);
	if (It == ValMap.end()) // No, visit it now.
	M = calculateGraphs(Callee, Stack, NextID, ValMap);
	else // Yes, get it's number.
	M = It->second;
	if (M < Min) Min = M;
	}

	assert(ValMap[F] == MyID && "SCC construction assumption wrong!");
	if (Min != MyID)
	return Min; // This is part of a larger SCC!

	// If this is a new SCC, process it now.
	if (Stack.back() == F) { // Special case the single "SCC" case here.
	DOUT << "Visiting single node SCC #: " << MyID << " fn: "
	<< F->getName() << "\n";
	Stack.pop_back();
	DOUT << " [BU] Calculating graph for: " << F->getName()<< "\n";
	calculateGraph(Graph);
	DOUT << " [BU] Done inlining: " << F->getName() << " ["
	<< Graph.getGraphSize() << "+" << Graph.getAuxFunctionCalls().size()
	<< "]\n";

	if (MaxSCC < 1) MaxSCC = 1;

	// Should we revisit the graph? Only do it if there are now new resolvable
	// callees.
	GetAllAuxCallees(Graph, CalleeFunctions);
	if (!CalleeFunctions.empty()) {
	DOUT << "Recalculating " << F->getName() << " due to new knowledge\n";
	ValMap.erase(F);
	return calculateGraphs(F, Stack, NextID, ValMap);
	} else {
	ValMap[F] = ~0U;
	}
	return MyID;

	} else {
	// SCCFunctions - Keep track of the functions in the current SCC
	//
	std::vector<DSGraph*> SCCGraphs;

	unsigned SCCSize = 1;
	Function *NF = Stack.back();
	ValMap[NF] = ~0U;
	DSGraph &SCCGraph = getDSGraph(*NF);

	// First thing first, collapse all of the DSGraphs into a single graph for
	// the entire SCC. Splice all of the graphs into one and discard all of the
	// old graphs.
	//
	while (NF != F) {
	Stack.pop_back();
	NF = Stack.back();
	ValMap[NF] = ~0U;

	DSGraph &NFG = getDSGraph(*NF);

	// Update the Function -> DSG map.
	for (DSGraph::retnodes_iterator I = NFG.retnodes_begin(),
	E = NFG.retnodes_end(); I != E; ++I)
	DSInfo[I->first] = &SCCGraph;

	SCCGraph.spliceFrom(NFG);
	delete &NFG;

	++SCCSize;
	}
	Stack.pop_back();

	DOUT << "Calculating graph for SCC #: " << MyID << " of size: "
	<< SCCSize << "\n";

	// Compute the Max SCC Size.
	if (MaxSCC < SCCSize)
	MaxSCC = SCCSize;

	// Clean up the graph before we start inlining a bunch again...
	SCCGraph.removeDeadNodes(DSGraph::KeepUnreachableGlobals);

	// Now that we have one big happy family, resolve all of the call sites in
	// the graph...
	calculateGraph(SCCGraph);
	DOUT << " [BU] Done inlining SCC [" << SCCGraph.getGraphSize()
	<< "+" << SCCGraph.getAuxFunctionCalls().size() << "]\n"
	<< "DONE with SCC #: " << MyID << "\n";

	// We never have to revisit "SCC" processed functions...
	return MyID;
	}

	return MyID; // == Min
	}


	// releaseMemory - If the pass pipeline is done with this pass, we can release
	// our memory... here...
	//
	void BUDataStructures::releaseMyMemory() {
	for (hash_map<Function, DSGraph>::iterator I = DSInfo.begin(),
	E = DSInfo.end(); I != E; ++I) {
	I->second->getReturnNodes().erase(I->first);
	if (I->second->getReturnNodes().empty())
	delete I->second;
	}

	// Empty map so next time memory is released, data structures are not
	// re-deleted.
	DSInfo.clear();
	delete GlobalsGraph;
	GlobalsGraph = 0;
	}

	DSGraph &BUDataStructures::CreateGraphForExternalFunction(const Function &Fn) {
	Function F = const_cast<Function>(&Fn);
	DSGraph *DSG = new DSGraph(GlobalECs, GlobalsGraph->getTargetData());
	DSInfo[F] = DSG;
	DSG->setGlobalsGraph(GlobalsGraph);
	DSG->setPrintAuxCalls();

	// Add function to the graph.
	DSG->getReturnNodes().insert(std::make_pair(F, DSNodeHandle()));

	if (F->getName() == "free") { // Taking the address of free.

	// Free should take a single pointer argument, mark it as heap memory.
	DSNodeHandle N(new DSNode(0, DSG));
	N.getNode()->setHeapMarker();
	DSG->getNodeForValue(F->arg_begin()).mergeWith(N);

	} else {
	cerr << "Unrecognized external function: " << F->getName() << "\n";
	abort();
	}

	return *DSG;
	}

	void BUDataStructures::calculateGraph(DSGraph &Graph) {
	// If this graph contains the main function, clone the globals graph into this
	// graph before we inline callees and other fun stuff.
	bool ContainsMain = false;
	DSGraph::ReturnNodesTy &ReturnNodes = Graph.getReturnNodes();

	for (DSGraph::ReturnNodesTy::iterator I = ReturnNodes.begin(),
	E = ReturnNodes.end(); I != E; ++I)
	if (I->first->hasExternalLinkage() && I->first->getName() == "main") {
	ContainsMain = true;
	break;
	}

	// If this graph contains main, copy the contents of the globals graph over.
	// Note that this is required for correctness. If a callee contains a use
	// of a global, we have to make sure to link up nodes due to global-argument
	// bindings.
	if (ContainsMain) {
	const DSGraph &GG = *Graph.getGlobalsGraph();
	ReachabilityCloner RC(Graph, GG,
	DSGraph::DontCloneCallNodes \|
	DSGraph::DontCloneAuxCallNodes);

	// Clone the global nodes into this graph.
	for (DSScalarMap::global_iterator I = GG.getScalarMap().global_begin(),
	E = GG.getScalarMap().global_end(); I != E; ++I)
	if (isa<GlobalVariable>(*I))
	RC.getClonedNH(GG.getNodeForValue(*I));
	}


	// Move our call site list into TempFCs so that inline call sites go into the
	// new call site list and doesn't invalidate our iterators!
	std::list<DSCallSite> TempFCs;
	std::list<DSCallSite> &AuxCallsList = Graph.getAuxFunctionCalls();
	TempFCs.swap(AuxCallsList);

	bool Printed = false;
	std::vector<Function*> CalledFuncs;
	while (!TempFCs.empty()) {
	DSCallSite &CS = *TempFCs.begin();

	CalledFuncs.clear();

	// Fast path for noop calls. Note that we don't care about merging globals
	// in the callee with nodes in the caller here.
	if (CS.getRetVal().isNull() && CS.getNumPtrArgs() == 0) {
	TempFCs.erase(TempFCs.begin());
	continue;
	}

	GetAllCallees(CS, CalledFuncs);

	if (CalledFuncs.empty()) {
	// Remember that we could not resolve this yet!
	AuxCallsList.splice(AuxCallsList.end(), TempFCs, TempFCs.begin());
	continue;
	} else {
	DSGraph *GI;
	Instruction *TheCall = CS.getCallSite().getInstruction();

	if (CalledFuncs.size() == 1) {
	Function *Callee = CalledFuncs[0];
	ActualCallees.insert(std::make_pair(TheCall, Callee));

	// Get the data structure graph for the called function.
	GI = &getDSGraph(*Callee); // Graph to inline
	DOUT << " Inlining graph for " << Callee->getName()
	<< "[" << GI->getGraphSize() << "+"
	<< GI->getAuxFunctionCalls().size() << "] into '"
	<< Graph.getFunctionNames() << "' [" << Graph.getGraphSize() <<"+"
	<< Graph.getAuxFunctionCalls().size() << "]\n";
	Graph.mergeInGraph(CS, Callee, GI,
	DSGraph::StripAllocaBit\|DSGraph::DontCloneCallNodes);
	++NumBUInlines;
	} else {
	if (!Printed)
	DEBUG(std::cerr << "In Fns: " << Graph.getFunctionNames() << "\n");
	DEBUG(std::cerr << " calls " << CalledFuncs.size()
	<< " fns from site: " << CS.getCallSite().getInstruction()
	<< " " << *CS.getCallSite().getInstruction());
	DEBUG(std::cerr << " Fns =");
	unsigned NumPrinted = 0;

	for (std::vector<Function*>::iterator I = CalledFuncs.begin(),
	E = CalledFuncs.end(); I != E; ++I) {
	if (NumPrinted++ < 8) cerr << " " << (*I)->getName();

	// Add the call edges to the call graph.
	ActualCallees.insert(std::make_pair(TheCall, *I));
	}
	cerr << "\n";

	// See if we already computed a graph for this set of callees.
	std::sort(CalledFuncs.begin(), CalledFuncs.end());
	std::pair<DSGraph*, std::vector<DSNodeHandle> > &IndCallGraph =
	(*IndCallGraphMap)[CalledFuncs];

	if (IndCallGraph.first == 0) {
	std::vector<Function*>::iterator I = CalledFuncs.begin(),
	E = CalledFuncs.end();

	// Start with a copy of the first graph.
	GI = IndCallGraph.first = new DSGraph(getDSGraph(**I), GlobalECs);
	GI->setGlobalsGraph(Graph.getGlobalsGraph());
	std::vector<DSNodeHandle> &Args = IndCallGraph.second;

	// Get the argument nodes for the first callee. The return value is
	// the 0th index in the vector.
	GI->getFunctionArgumentsForCall(*I, Args);

	// Merge all of the other callees into this graph.
	for (++I; I != E; ++I) {
	// If the graph already contains the nodes for the function, don't
	// bother merging it in again.
	if (!GI->containsFunction(*I)) {
	GI->cloneInto(getDSGraph(**I));
	++NumBUInlines;
	}

	std::vector<DSNodeHandle> NextArgs;
	GI->getFunctionArgumentsForCall(*I, NextArgs);
	unsigned i = 0, e = Args.size();
	for (; i != e; ++i) {
	if (i == NextArgs.size()) break;
	Args[i].mergeWith(NextArgs[i]);
	}
	for (e = NextArgs.size(); i != e; ++i)
	Args.push_back(NextArgs[i]);
	}

	// Clean up the final graph!
	GI->removeDeadNodes(DSGraph::KeepUnreachableGlobals);
	} else {
	cerr << "*\n* RECYCLED GRAPH *\n*\n";
	}

	GI = IndCallGraph.first;

	// Merge the unified graph into this graph now.
	DOUT << " Inlining multi callee graph "
	<< "[" << GI->getGraphSize() << "+"
	<< GI->getAuxFunctionCalls().size() << "] into '"
	<< Graph.getFunctionNames() << "' [" << Graph.getGraphSize() <<"+"
	<< Graph.getAuxFunctionCalls().size() << "]\n";

	Graph.mergeInGraph(CS, IndCallGraph.second, *GI,
	DSGraph::StripAllocaBit \|
	DSGraph::DontCloneCallNodes);
	++NumBUInlines;
	}
	}
	TempFCs.erase(TempFCs.begin());
	}

	// Recompute the Incomplete markers
	Graph.maskIncompleteMarkers();
	Graph.markIncompleteNodes(DSGraph::MarkFormalArgs);

	// Delete dead nodes. Treat globals that are unreachable but that can
	// reach live nodes as live.
	Graph.removeDeadNodes(DSGraph::KeepUnreachableGlobals);

	// When this graph is finalized, clone the globals in the graph into the
	// globals graph to make sure it has everything, from all graphs.
	DSScalarMap &MainSM = Graph.getScalarMap();
	ReachabilityCloner RC(*GlobalsGraph, Graph, DSGraph::StripAllocaBit);

	// Clone everything reachable from globals in the function graph into the
	// globals graph.
	for (DSScalarMap::global_iterator I = MainSM.global_begin(),
	E = MainSM.global_end(); I != E; ++I)
	RC.getClonedNH(MainSM[*I]);

	//Graph.writeGraphToFile(cerr, "bu_" + F.getName());
	}

	static const Function getFnForValue(const Value V) {
	if (const Instruction *I = dyn_cast<Instruction>(V))
	return I->getParent()->getParent();
	else if (const Argument *A = dyn_cast<Argument>(V))
	return A->getParent();
	else if (const BasicBlock *BB = dyn_cast<BasicBlock>(V))
	return BB->getParent();
	return 0;
	}

	/// deleteValue/copyValue - Interfaces to update the DSGraphs in the program.
	/// These correspond to the interfaces defined in the AliasAnalysis class.
	void BUDataStructures::deleteValue(Value *V) {
	if (const Function *F = getFnForValue(V)) { // Function local value?
	// If this is a function local value, just delete it from the scalar map!
	getDSGraph(*F).getScalarMap().eraseIfExists(V);
	return;
	}

	if (Function *F = dyn_cast<Function>(V)) {
	assert(getDSGraph(*F).getReturnNodes().size() == 1 &&
	"cannot handle scc's");
	delete DSInfo[F];
	DSInfo.erase(F);
	return;
	}

	assert(!isa<GlobalVariable>(V) && "Do not know how to delete GV's yet!");
	}

	void BUDataStructures::copyValue(Value From, Value To) {
	if (From == To) return;
	if (const Function *F = getFnForValue(From)) { // Function local value?
	// If this is a function local value, just delete it from the scalar map!
	getDSGraph(*F).getScalarMap().copyScalarIfExists(From, To);
	return;
	}

	if (Function *FromF = dyn_cast<Function>(From)) {
	Function *ToF = cast<Function>(To);
	assert(!DSInfo.count(ToF) && "New Function already exists!");
	DSGraph NG = new DSGraph(getDSGraph(FromF), GlobalECs);
	DSInfo[ToF] = NG;
	assert(NG->getReturnNodes().size() == 1 && "Cannot copy SCC's yet!");

	// Change the Function* is the returnnodes map to the ToF.
	DSNodeHandle Ret = NG->retnodes_begin()->second;
	NG->getReturnNodes().clear();
	NG->getReturnNodes()[ToF] = Ret;
	return;
	}

	if (const Function *F = getFnForValue(To)) {
	DSGraph &G = getDSGraph(*F);
	G.getScalarMap().copyScalarIfExists(From, To);
	return;
	}

	cerr << *From;
	cerr << *To;
	assert(0 && "Do not know how to copy this yet!");
	abort();
	}